The acting chief of Scotland Yard has said the phone-hacking scandal had "tarnished" the force's reputation, as another police chief dismissed one of David Cameron's plans for radical reform as "simply stupid".

Tim Godwin, acting commissioner after the resignation of Sir Paul Stephenson, said it was "a matter of great regret" the force had suffered criticism over its actions and ethical standards, after revelations of repeated private dinners between its top officers and senior executives at the News of the World.

Godwin told the Metropolitan Police Authority that the force faced "very, very, very challenging times … If I could put the clock back, I would like to do that."

The fallout from the scandal led to Stephenson's resignation as commissioner and that of John Yates as Britain's top counterterrorism officer. Stephenson had met NoW bosses numerous times and ended up employing the paper's former deputy editor, Neil Wallis, in a senior public relations role.

But Godwin denied corruption was endemic in the force, or that it had "let its guard down", and promised a clean up.

The reverberations of the hacking scandal throughout policing have led to calls for radical reform. But one of the UK's top officers yesterday rubbished the prime minister's call for foreign police chiefs to be brought in to run British forces.

Sir Hugh Orde, president of the Association of Chief Police Officers, said: "The notion that you can ship someone in from another country to run a police force in a different environment and a different culture is simply stupid."

In the Commons last Wednesday, Cameron told MPs: "Why shouldn't someone with a different skill set be able to join the police force in a senior role? Why shouldn't someone who has been a proven success overseas be able to help turn around a force at home?"

Orde, a possible candidate to be the next Met commissioner, also ridiculed the idea that people from non-police backgrounds could be "parachuted" into senior roles in a force. "The last thing I need as a chief constable is someone from another profession on work experience. The decisions I have to make are potentially life or death."

Orde said he had written to Cameron, inviting him to come and meet the leadership of the service.

In the last selection process for commissioner, Orde came second. One factor thought to count against him was his outspokenness.

On Thursday he said he would continue to speak out. "The notion the new chief officer will be silenced is utterly flawed and certainly not a world I would be prepared to operate in," he said.

He dismissed suggestions the Met should be stripped of its national functions such as counterterrorism as "foolhardy and foolish", especially ahead of the 2012 London Olympics.He also warned that police should not "pull up the drawbridge" and stop talking to the media, saying chief officers had an "obligation" to explain the complexities of policing to journalists, and that to retreat would leave the police in a "bizarre and sterile world". Another potential candidate for the Met commissionership has also questioned Cameron's remarks about the need for radical reform of police leadership. Writing in today's Guardian, Sara Thornton, chief constable of Thames Valley, questions whether the plans were well thought out or an "expedient response to events".

Thornton, whose force covers Cameron's constituency, said: "The controversy surrounding illegal activity by News International and its relationship with politicians and the Met has caused questions to be asked about police leadership and culture. "The prime minister's statement to the Commons last week, saying he wanted to see 'how we can open up our police force and bring in fresh leadership', is prompting debate in the service … I remain unclear whether the proposal has been carefully considered or whether it was an expedient response to events."